The present invention generally relates to blood component harvesting and, more particularly, in one application to a method and apparatus for producing platelet products, namely a collection of harvested platelets having a determined yield associated therewith.
The utilization of blood taken from donors and infused into recipients is well known for purposes of treating medical emergencies and other conditions. More recently, selected blood components have been harvested from blood for subsequent infusion into recipients requiring blood component therapy. As used herein, xe2x80x9charvestingxe2x80x9d means the separation/removal of a particular type of blood component from remaining portions of the whole blood.
In order to harvest blood components, blood is removed from a donor by a needle assembly or other blood access device and is thereafter processed utilizing centrifugation or other appropriate separation techniques to isolate and collect the desired components. This procedure is carried out most effectively in an on-line, continuous process wherein blood is removed from a donor, processed through a disposable extracorporeal circuit to obtain the desired components, and returned to the donor. Once the harvested blood components are collected in this manner, it is often necessary to subject such components to an xe2x80x9coff-line yield determination technique.xe2x80x9d As used herein, xe2x80x9coff-line yield determination techniquexe2x80x9d means any laboratory analysis performed in accordance with a predetermined laboratory testing regime (i.e., utilizing a particular blood component counting technique with a specific predetermined apparatus and protocol). For instance, in the case of harvested platelets laboratory testing is required (e.g., governmental/industry regulations/standards) or otherwise desired to identify platelet yield prior to distribution. More particularly, under some circumstances associating a platelet yield (e.g., the number of platelets in a harvested collection or any other value from which such may be derived) within a particular collection of platelets may be integral in the provision of such as a platelet product.
Laboratory testing of blood components typically entails the use of expensive equipment and relatively time-consuming procedures, and therefore the use of off-line yield determination techniques is not feasible for many blood harvesting facilities. Consequently, these facilities are forced to ship their collections of harvested blood components to off-site, third-party laboratories meeting the relevant requirements. As can be appreciated, such third-party laboratory testing of harvested blood components adds significant cost and delay in the provision of blood component products.
In the latter regard, certain xe2x80x9con-line yield determination techniquesxe2x80x9d have been developed to assist blood component harvesting facilities in donor yield/schedule planning and donor-specific harvesting procedures. As used herein, xe2x80x9con-line yield determination techniquexe2x80x9d means any technique, other than off-line yield determination techniques (i.e., actual laboratory testing), to forecast the yield of harvested/collected blood components. Of particular interest, a platelet yield prediction technique has been developed which is based upon donor-specific physical data (e.g., donor blood volume, hematocrit, and platelet precount) and harvest procedure-specific information (e.g., needle information, device collection efficiency, volume of concurrent source plasma collection, whole blood and anticoagulant flow rates, anticoagulant infusion rate, and procedure duration). Relatedly, harvesting/collection monitoring techniques have been employed in which, for example, optical measurements are taken during platelet collection to determine platelet concentration from which platelet yield is determined. By way of example, each of the noted prediction and monitoring techniques are incorporated in the COBE Spectra(trademark), a product of Cobe BCT, Incorporated, 1201 Oak Street, Lakewood, Colo. 80215.
While such prediction and monitoring techniques have proven to be useful for planning purposes, experience reflects discrepancies between yield values generated thereby and the corresponding yield values obtained by off-line yield determination techniques. Moreover, it is generally believed that there is a laboratory-to-laboratory variance in determining yields, even when employing similar off-line yield determination techniques.
The present invention is directed to a method and apparatus for producing blood component products, namely a collection of harvested blood components having a determined yield associated therewith. The invention is based in part upon a recognition that variability in off-line yield determination techniques, utilizing for instance predetermined laboratory counting equipment and procedures, should be accounted for in determining the blood component product yield by on-line yield determination techniques.
In one aspect, the present invention is a method for providing a desired blood component product, namely a collection of a plurality of a desired blood component having a determined yield, in relation to a predetermined off-line yield determination technique. The method comprises two general steps: obtaining a collection of desired blood components and determining the yield of such blood components by at least one on-line yield determination technique. More particularly, a desired blood component (e.g., platelets) is harvested from a source of whole blood (e.g., a donor) in an appropriate manner (e.g., centrifugation). A first calibration factor is established for the at least one predetermined on-line yield determination technique, more particularly a predetermined yield prediction technique, in relation to the predetermined off-line yield determination technique. As it is employed herein, the term xe2x80x9cpredetermined yield prediction techniquexe2x80x9d means any technique, not involving measurements conducted on the harvested blood components, that may be employed to predict blood component yield for a given blood component harvesting operation. The predetermined yield prediction technique is utilized to obtain a first predicted yield value for the harvesting operation, and the first calibration factor is thereafter applied to the first predicted yield value to obtain a second predicted yield value. The determined yield for the collected blood components is thereafter derived at least in part from this second predicted yield value. Consequently, when the collected blood components are packaged, the determined yield may be associated therewith by recording the yield in some manner (e.g., by indicating the yield directly on the packaging, or by inputting the yield into a data base with a corresponding identifier which is also indicated on the packaging), such that a blood component product is provided.
The method of the above-identified aspect of the present invention may further comprise the step of monitoring the harvested blood components during at least a portion of the harvesting step to obtain a first monitored yield value, namely by utilizing another on-line yield determination technique in the nature of a predetermined yield monitoring technique. As employed herein, the term xe2x80x9cpredetermined yield monitoring techniquexe2x80x9d means any technique, involving measurements conducted in conjunction with a harvesting operation on harvested blood components, that may be employed to monitor blood component yield for the blood component harvesting operation. A second calibration factor may then be established for the predetermined yield monitoring technique in relation to the predetermined off-line yield determination technique. Once this second calibration factor is established, it may be applied to the first monitored yield value to obtain a second monitored yield value. In order to enhance accuracy, the determined yield may then be derived from both the second predicted yield value and the second monitored yield value.
In addition to increasing the potential for achieving an accurate determined yield by utilizing both the second predicted yield value and the second monitored yield value, generating both such yield values allows for an assessment of the likelihood that a determined yield value will fall within an acceptable range of accuracy, thereby enhancing quality control. More particularly, if in appropriately comparing the second predicted yield value and second monitored yield value a determination is made that the difference therebetween is outside a certain predefined statistical parameter, the collection of blood components can be sent to a laboratory for a determination of yield by, for instance, the predetermined off-line yield determination technique.
The first and/or second calibration factors utilized in the method of the above-identified aspect may each be established by conducting a blood component harvesting operation for at least one, and preferably for a plurality of first blood sources to obtain an associated first blood component sample(s). The predetermined yield prediction technique may thus be employed for each of such first blood component samples to obtain an associated first predicted yield value, and/or the predetermined yield monitoring technique may be utilized for each of such samples to obtain an associated first monitored yield value. Each of the first blood component samples may also be subjected to the predetermined off-line yield determination technique to obtain corresponding off-line measured yield values for such samples.
Having obtained the foregoing yield values, an initializing first calibration factor may be obtained for each of the first blood component samples by dividing the off-line measured yield value by the associated first predicted yield value for each such sample. The mean of these initializing first calibration factors may then taken to establish the first calibration factor. Similarly, an initializing second calibration factor may be obtained for each of the first blood component samples by dividing the off-line measured yield value by the associated first monitored yield value. The mean of these initializing second calibration factors may then be taken to establish the second calibration factor. As can be appreciated, the size of the calibration group (e.g., first blood sources) will of course determine in part the statistical significance of the respective first and second calibration factors.
In the event that the first and second calibration factors are obtained in the above-described manner, the related information may be utilized by the present invention by further potential steps to ensure that such calibration factors are properly maintained. For instance, at least one, and preferably a plurality of second blood sources may be subjected to an appropriate separation procedure to obtain an associated second blood component sample(s). The yield for each of these second blood component samples may be obtained by each of the predetermined yield prediction technique, the predetermined yield monitoring technique, and the predetermined off-line yield determination technique. A test first calibration factor may be obtained for each of the second blood component samples by dividing the off-line measured yield value by the first predicted yield value. Similarly, a test second calibration factor for each of the second blood component samples may be obtained by dividing the off-line measured yield value by the first monitored yield value. The mean may be taken of the plurality of first test calibration factors, and a mean may be taken for the plurality of test second calibration factors. Moreover, a mean may be taken of the combination of the initializing first calibration factors and the test first calibration factors, and similarly for the combination of the initializing second calibration factors and the test second calibration factors. The mean of the test first calibration factors and/or the mean of the combination of initializing/test first calibration factors may be utilized to verify the suitability of the first calibration factor, and similarly the mean of the test second calibration factors and/or the mean of the combination of initializing/test second calibration factors may be utilized to verify the suitability of the second calibration factor.
In another aspect, the present invention is a system for providing a blood component product, namely a collection of harvested blood components having a determined yield provided in accordance with at least one on-line yield determination technique. The system generally entails the harvesting of such blood components, the provision of predetermined information, and the use of such information to obtain the yield of harvested blood components by such on-line yield determination technique(s) to provide the desired blood component product.
More particularly, the system includes a means for harvesting the blood components from a source of blood. As a result, a plurality of blood components are collected for distribution as a blood component product after determining the yield thereof in accordance with the present invention. The yield of the harvested blood components is based, in part, upon certain categories of information provided by an operator of the system to appropriate portions thereof. More particularly, a system component (e.g., keyboard and microprocessor) is provided for inputting/receiving: a first set of information relating to the source of the blood (e.g., donor weight, height); and a second set of information relating to the means for harvesting (e.g., collection efficiency, single or dual needle configuration). Based upon this operator-input information, a system component (e.g., microprocessor) generates a first predicted yield value.
The system further includes a system component(s) for providing a first calibration factor, based upon the system component(s) which generates the predicted yield value in relation to a predetermined off-line yield determination technique. This predetermined off-line yield determination technique allows/provides for an off-line measured yield value for the harvested blood components. For instance, the off-line measured yield value and predicted yield value for a plurality of runs on the system may be utilized to statistically generate the first calibration factor. Based upon this information, a system component(s) generates the determined yield at least in part by the application of the first calibration factor to the predicted yield value. Consequently, the harvested blood components may be packaged and the determined yield associated therewith to provide the desired blood component product.
In order to further enhance the potential for a desired degree of accuracy for the determined yield, the above-identified system may further include a system component(s) for providing another on-line yield determination technique, namely to provide a monitored yield value for the harvested blood components based upon a monitoring of the harvested blood components. Consequently, a system component(s) may provide a second calibration factor based upon the system component(s) which provides the monitored yield value in relation to the predetermined off-line yield determination technique. In this case, the system component(s) which generates the determined yield may thus utilize both the application of the first calibration factor to the predicted yield value, as well as the application of the second calibration factor to the monitored yield value, to obtain the determined yield.
In another aspect, the present invention is an assembly for providing a blood component product, namely a collection of harvested blood components having a determined yield pursuant to at least two on-line yield determination techniques. More particularly, a means is provided for harvesting (e.g., a centrifuge) the desired blood components (e.g., platelets) from the source of blood. Furthermore, means are provided for providing a first predicted yield value of the harvested blood components and means are also provided for monitoring the harvested blood components to obtain a first monitored yield value. A first calibration factor is applied to the first predicted yield value and a second calibration factor is applied to the first monitored yield value to obtain a second predicted yield value and second monitored yield value, respectively. The first and second calibration factors are based upon the means for providing the first predicted yield value and the means for monitoring, respectively, both in relation to a predetermined off-line yield determination technique. The determined yield is then derived from the second predicted yield value and the second monitored yield value such that when the collected blood components are packaged, a blood component product may be provided, namely one having a determined blood component yield with a specified confidence level or probability of not being less than the yield as would be measured by the predetermined off-line yield determination technique (e.g., laboratory equipment/protocol).
The method and apparatus of the present invention have particular applicability to platelet harvesting operations. In particular, it is believed that platelet products produced in accordance with the present invention largely reduce the need for subjecting harvested platelet products to subsequent laboratory testing before distribution.